Anything that prevents thermal convection will save energy. Therefore, either heat trap will work, although it does not have to be 360 degrees, it just has to drop down after leaving the water heater. Thermal wraps probably do not save as much money as it would cost to buy them and many water heaters have a caution against using them printed on the side of the heater.

: Do heat traps installed just outside of a hot water heater really conserve that much energy? If so, what type is better: the check valve type (nipple with ball inside) or the 360 degree loop in pipe? Do the insulating blankets (sold as a kit) that wrap around hot water heater really make that much difference in preventing heat loss?